BY DAVID KRONKE >TV CRITIC

Last year, in "Dexter's" second season, Dexter Morgan's extracurricular activities - murdering killers who had evaded justice - were exposed, and he spent much of the season getting painted into a corner, only to ingeniously (and fairly credibly) wriggle free in the end.

Topping that story line seems fairly insurmountable, so as season three begins, things are looking up for Dexter (Michael C. Hall) as he settles into what, for him, is "a nice, normal world." His relationship with Rita (Julie Benz) is going swimmingly; Rita even exults, "Everything's falling into place for the first time in my life."

Oh, Rita, Rita: Never say that on a TV show. Because you know exactly what's coming next.

Sure enough, while on a seemingly routine mission to off a guy who murdered two co-eds but was never captured, Dexter walks into a fight; his quarry escapes, but the other man attacks Dexter and is killed in the brawl.

Making matters worse, the dead man is the brother of Miguel Prado (Jimmy Smits), a dedicated and extremely successful local prosecutor.

Prado takes a special interest in the special interest Dexter takes in the case, and they become buddies and, even, conspirators. The attention lavished upon a fairly humdrum subplot suggests that Prado may have secrets of his own, however.

Through four episodes, "Dexter's" third season hasn't really approached the inspired anxiety of those preceding it. Still, the story line's intriguing, and Hall's performance as the haunted and demented character remains compelling.

HBO adds a couple of new comedies to its schedule tonight, but they probably put the wrong one immediately after "Entourage."

"The Life and Times of Tim" is the funnier entry, but to get to it, you'll have to sit through "Little Britain USA."

Recalling the deadpan improvisation and bargain-basement animation of "Dr. Katz, Professional Therapist," "The Life and Times of Tim" is a no-budget animated comedy about Tim (voiced by series creator Steve Dildarian), a hapless human void whose girlfriend Amy (Maryjane Otto) is even unluckier than he is, if only because she's dating him by choice.

Each episode features two short installments, in which Tim either makes a terribly stupid decision as coaxed by those around him (his idiot boss, his reprobate priest) or of his own volition. The results are invariably humiliating, and frequently come in front of Amy's parents.

Tim's stammering, vaguely clueless sadsack persona is reminiscent of Ray Romano. The repetitiveness of the premise is leavened by the agreeably low-key fashion in which the jokes are sold. Though it has its share of laughs, the show would probably make more sense airing on Adult Swim or Comedy Central - it's not quite sophisticated or urbane enough for HBO.

But "Tim" is practically the soaring rhetoric of John Milton compared to "Little Britain USA," in which a British sketch-comedy troupe tries to explain to Americans from an across-the-pond perspective. Creators Matt Lucas and David Walliams try to ameliorate their attacks on stateside mores by including unflattering portraits of British characters, as well, but the result still feels pretty condescending.

David Kronke, (818) 73-3638 david.kronke@dailynews.com

www.insidesocal.com/tv/

reviews>

DEXTER

>What: Season-three premiere of the adventures of 's favorite serial killer.

>Where: Showtime.

>When: 9 pm Sunday

>In a nutshell: Not as intense as in previous seasons, but still intriguing and cleverly concocted.

THE LIFE AND TIMES OF TIM

>What: Animated comedy about a loser, losing constantly.

>Where: HBO.

>When: 11 pm Sunday

>In a nutshell: Droll and deadpan.

LITTLE BRITAIN USA

>What: The British sketch-comedy series decamps to our shores.

>Where: HBO.

>When: 10:30  pm Sunday

>In a nutshell: Something got lost in translation.